Hydraulic transmission.



L. E. HOPKINS.

HYDRAULIC TRANsMlssIoN.

APPLIUATION FILED MAY 27, 1913.

Patented Mar. 24, 1914 2 SHEETS-SHEBT l.

L. E. HOPKINS. HYDRAULIC TRANSMISSION. APPLIOATI-ON P ILBD MAY 27, 191s.

Patented' Mar. 24, 1914.

2 SHEETS-SHEET z.

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UNITED STATES PATEN OFFICE.

LEWIS4 ERNEST HOPnKINS, 0F CARDI'FF, 'WALES.`

HYDRAULIC SMISSION.

Specification of Letters Patent. Patented Mar, 24, 1914,

Application l-'ed May 27, 1918. Serial No. 770,155.

hydraulic machine, which can be employed as a pump or a' motor, is ofthe type in which a ro-tor secured toa shaft is formed with a pluralityof radially situated cyl1ndersf equi-angularly situated relativelytoeach other, each cylinder being fitted with a piston. These pistonsare so connected to the stator that. in the revolution of the rotor theyare constrained to move in a path `which is approximately a circle,whose center is eccentric to the axis of revolution of therotor wherebywith each revolution of the rotor each piston performs a double strokewithin its cylinder. Moreover the liquid Hows intoand out of thecylinders from 'and into, respectively, an annular space providedbetween the outer boundary of the rotor .and the stator casing.

Now according` to the present invention the liquid is supplied to anddelivered from the said annular space by a pair -of passages which aresituated approximately at the opposite ends of-a diameter which containsthe center of the eccentric circular orbitof the pistons, and theannular space is divided into two portions by a pair of partitionssituated approximately dia-metrally opposite each other, the saidpartitions being carried by a disk so mounted tliatthe said partitionsare adapted to be angularly displaced within the annular spacerelatively to the stator, means being provided whereby the partitionscan be set to occupy any desired angular position relatively to the linejoining the admission and eduction passages for the liquid.

The length of eachpartition, as measured in the direction of thecircumferenceof the annular passage,

ders in order to avoid any cylinder from being 1n communication with theannular space on both sides of a partition for more than a relativelysmall portion of, time. lVlth this arrangement it will be observed that,if the partitions are placed with the llne which joins their centers atright angles tio the line through the admission and eductlon passagesand the rotor is rotated,

-then from and to each half of the annular space j ust as much liquidwill be drawn into the cyl1nders as will be evacuated therefrom andtherefore no liquid will flow from thev admission to the eductionpassage. If from this position the partitions are angularly displaced,more liquid will be drawn into the cylinders from one half of theannular space than will be evacuated into that half t is madeapproximately equal to the diameter of the cylin-` space from thecylinders, whereas from the i other half space less liquid Will bedrawnl into thev cylinders than 'will be evacuated therefrom.Accordingly, liquid will enter.

the annular space on one side of the two partitions from one of t-hepassages and an equal quantity of liquid will be delivered through theother passage from the portion of the annular space on the other sideofthe partitions. f inner surface of the upposing the rotor to revolvein'either direction and the parutions to be angularly ldisplaced in thesame direction, then liquid will be admittedl through the passage whichlis nearer the center ofy the eccentric orbit of the pistons and will bedelivered through the other-passage. If, on the other hand,

the partitions are angularly displaced in a direction opposite to thatof the rotation of the rotor the direction of the flow of liquid will bereversed.

lVhen the partitions are angularlysituated so as to be as nearly in theline of the admission and eduction passages as possible, withoutobstructing the fiow through' .those passages, then the quantity ofliquid transferred fro-m one passage to the other,

per revolution of the rotor, will be equal to the volume of displacementof all the pistons carried by the rotor. When the partiltions aresituated in an intermediate position\ the quantity of liquid transferredfrom one passage to the other will be a fraction of the totaldisplacement volume,

. the magnitudeof which will depend on the angle through which thepartitions have been shifted from a line at right-angles to the line oflthe two passages. If, instead of the rotor being driven by mechanicalenergy applied to the shaft to which it is secured, in which case the'machine will operate as a pump, high-pressure liquid is suplied throughone of the passages and the other passage is in communication with aspace of low pressure, the liquid in forcing its way from the first tothe second-mentioned passage will rotate the rotor against a resistance,and the machine will operate -as a motor.I With' a given difference ofpressure the torque exerted will depend on the angular situation of thepartitions and the expenditure of liquid willcorrespondinglyI vary,enabling the power of the motor to be varied, within wide limits,Without altering the pressure of the urging liquid. o-r the speed ofrevolution of the rotor.

When the rotor is urged by high-pressure fluid, as above described, thedirection in which it will rotate can be reversed b altering thedirection of the angular shi t also to lower weights.

Suppose, for the purpose of raising a weight, the machine is suppliedwith highpressure water which water is vdelivered into a low-pressuretank and subsequently the same weight is required to be lowered Topermit the wei ht to be lowered the partitions must be s ifted somewhattoward the neutral position from that which they ,occupied Vwhenhoisting, the weight will then be allowed to run down and in so doingwill reverse the direction of rotation of the rotor and cause it tooperate as a pump and transfer a portion of the water from thelow-pressure tank to the high-pressure source and so store up' someenergy for the next hoisting operation. In this manner the controllingeffect of a brake will be derived, but instead of the energy of descentYbeing wasted in friction it will be partially conserved for future use.

Besides being used as a pump or a motor or both combined, as justdescribed, one or a couple of such hydraulic machines may be employed asa variable speed, and reversing, transmission-organ in which liquidforced by one of the machines by the application of mechanical energy tothe shaft of its rotor is delivered to the other machine and the shaftof its rotor urged to rotate against a y resistance, the li uid beingreturned from the second machine to the first in a closed continuouscircuit.

If the partitions of the two machines are from the admission to theeduction passage in one machine during a revolution differs from thattransferred in the other machine during a revolutionv thereof, then thespeed of revolution of the one rotor must be so much greater or lessthan that of the other ,in the inverse ratio to that of the ratio ofvolumes transferred. By varying the transferred volume of liquid of onemachine or of both machines oppositely or differentially, power can betransmitted with a velocity ratio capable of being varied in a gradualmanner and within very wide limits. Sucha combination interposed betweenthe engines and the driving wheels of a motor car could be substitutedfor the change-speed gear hitherto in use, and provide an unlimitedrange of speed-ratio values.

Any appropriate known device for constraining the orbital motion of thepistons may be adopted, and preferably that in which each piston isunited by a connecting-rod to a pin secured to the stator, the one pinserving in common for all the pistons. Also any suitable means may beemployed for shift-ing the angular position of the partitions as, orexample, spur-Wheels, spur-wheel and rack or sector, or Worin-and-Worm-wheel. By the use of the latter the partitions will be retainedwhere set without other means for locking.

Packing rings and strips are employed to insure stanch joints in amanner employed for like purposes in other fluid-pressure machines.

The above described invention is illustrated on the accompanyingdrawings by an application thereof as a variable speedratio and,reversing rotary power-transmitter such as may, for example, besubstituted in motor-cars for the multiple, spurwheel, speed-gearshitherto in use.

In these drawings Figure lis a longitudinal section of the mechanism,and Fig. 2 is a part end elevation of the stator with the cover androtor removed. Fig. 3 is a transverse section taken alongvthe line 3 3of Fig. 1, and Fig. 4 is the central portion of the plan view of themechanism.

In these figures, a is the driving shaft which connects the car-enginewith the rotor A of the pump, and b is the driven shaft which connectsthe rotor B of the hydraulicy so set that the volume of liquidtransferred vlatter are located approximately dialnet-rally motor withthe Cardan shaft by which the l power is transmittedto thedriving-villieelsv of the car. According to this construction therotorsof both the pump and the h draulic-motor lare .contained Within t e samecasing C, and the liquid delivered by the pump nds its Way by" a passagewithin the casing to the motor and returns to the pump through anothersimilar passa'e. 4

In each rotor A and B are provided eight radially-bored cylinders, eachfitted with pistons. Seven pist-ons Z 'd of the pump are, byconnecting-rods e e, attached to a strap e which embraces a pin F whichis secured to the stator, the said strap and the rod-extension thereofserving to connect the eighth piston do to the pin F. By suchmeans, oneach revolution of the rotor the pistons will perform a double-strokeWithin their respective cylinders, the length of the stroke being twicethe radial dist-ance be, tween the axis of rotation of the rotor and theaxis of the pin F.

It will be observed that the construction is such that the same pin Fserves to determine the orbital path of the pistons g ofthe hydraulicmotor-rotor B as Well asthose of the ump-rotor A. i

Tie pump-rotor A is connected tothe drivin shaft a by means of a flangea1 formed integrally with the shaft. The shaft and the rotor are mountedto rotate freely on a set of ball-bearings a3 on t-he one side andanother set of ball-bearings a4 o-n the other side. The motor-rotor B iscorrespondingly secured by the flange b1 tothe j driven shaft b andlikewise mounted ontWo sets of ball-bearings b3 and b4.

The entire space Within the case C isy oo cupied by liquid of alubricating character, such as oil for example, apertures fitted withscrew-plugs being provided for the purpose of admitting the liquid andpermitting the evacuation of the air.

Around each rotor an annular space c is provided, the spaces vc beinginterconnected by a passage c1, formed Within the upper side ofthe-casing, and a corresponding passage c2 formed Within the undersideof the casing. In the annular space c of the pump v are fitted twopartitions r, it which pro-V ject inwardly from the face of a disk Hwhich is interposed between the pump-rotor A and the cover 0 of thecasing and so mounted as to be angularly-displaceable about the aXis ofthe rotor.

According to Fig. 1 the angular displacement of the disk H and itspartitions, Whichl opposite each other, are adapted to belett'octedthrough the medium of a spur-Wheel ,711 which is secured around the bossof the disk H and a uinion 7c which is secured to a partition-adjustingspindle K which tions such that t .angles tothe center line through theports to the before-mentioned passagesemerges Huid-.tight from thecasing C' through a stuing-box c.I v

Supposing the partitions k h areset in osieir center line is atrightvolving cyhnders. Accordingly in such aposition of the partitionsthe pump will be inoperative. If from this position the par- Ititionsare angularly displacedin the same direction as that ofthe rotation ofthe rotor, liquid will be drawn through the port nearer 'to-the pin Fand evacuated from the port opposite thereto. If, on the contrary,

the partitions' are angularlyfdisplaced ina -direction opposite to thatof rotation of the rotor, the direction of flow of the liquid throughthe pump- Will be reversed. The more the partit-ions are displaced fromthe neutrall posit-ions, the greater will be the quantity of liquidcirculated bythe pump, per revolution of the rotor.

As exhibited in the drawing, the' partitions Which divide the annularspace of the motor-stator into tvvo compartments are not angularlydisplaceable but are permanently located at c4, the extremity of thediameter which asses through the axis of the pin F (Fig. 21g andaretherefore so set as to admit to and deliver' from the stator, perrevolution of the rotor, the maximum quant-ity of liquid.

The rotor B of the motor being ident-ical with that of the rotor A ofthe pump, both rotors will run at practically the same speed when thepartitions h lz, of the pump are set tocirculate the maximum quant-ityof liquid.

By angularly displacing the partitions to- Ward the neutral position thevelocity-ratio of motor to pump will be gradually diminished and,inasmuch as the virtual-leverage of the liquid resistance to therotation of the pump-rotor Will thereby be correspondingly diminished,and, assuming the torque trans-v` mitted by the engines to thepump-rotor vto be unaltered, the liquid pressure set up in the casingand transmit-ted to the pistons of the motor Will be correspondinglyaugmented with equivalent increase of the torque exerted on thedriven-shaft b.

If instead of angularly displacing the partitions h la from the neutralposition in the direction of rotation of the rotor they are displaced ina contrary direction, the flow ol" liquid through the pump Will bereversed in direction and consequently the direction' ot' rotation ofthe rotor B of the motor will lne reversed.

As shown, the design is only a speed-reducing and reversing gear, but ifthe partitions 04 of the motor were also made angularly displaceable,the function of the mechanism would be extended to serve also as aspeed-increasing ear. In addition tov operating as a spec -reducing andreversinggear, the above described construction can very effectivelyserve the purpose of a brake. k Suppose the car to be descending anineline under the influence of gravity and it is requisite toabsorb aportion' of the energy which is being developed in order-to avoid undue.speed, then, under -such circumstances, what was the motor becomes apump and the liquid circulated thereby is adapted `to ser've as anabsorber of the superfluous energy Without incurring any detrimentaleffect on the mechanism. When what is normally the motor operates as apump, the circulation of the liquid through the pump proper will be inthe contrary direction to that which occurs when the pump proper isurging the machine in the forward direction.

The superfluous energy may be taken up by causing the liquid circulatedby What constitutes normally the motor to undergo very rapidly repeatedadmission to and evacuation from the cylinders of What is normally thepump, by displacing the partitions L toward theirneutral positions.Alternately the partitions may be so shifted as to constrict the flowthrough the ports-.leading from and to the before-mentioned passages clc2 and the superfluous energy be dissipated by the abrupt changes ofvelocity and consequent eddying-motion to which the liquid will besubjected.

I claim:

1. A rotary machine comprising a rotor formed with a plurality ofradially-directed cylinders fitted with pistons, means for connectingsaid pistons to the stator such that they pursue an orbital patheccentric to the axis of the rotor, an inclosing stator which providesan annular space around said rotor, a passage leading to Said annularspace and one leading therefrom, partitions dividing said annular spaceinto a plurality of compartments, and means for displacing said lpartitions angularly, relatively to the stator.

2. A rotary machine comprising a rotor formed with a plurality ofradially-directed cylinders fitted with pistons, means for connectingsaid pistons to the stator such that they pursue an orbital patheccentric to the axis of the rotor, an inclosing stator which providesan annular space around said rotor, a Apassage leading to said annularspace and one leading therefrom the ports of which are situatedapproximately at the extremities of a diameter of the stator whichcontains the center of the orbit of the pistons, partitions situatedapproximately diametrally opposite each other and carried by a disk andmeans for angularly displacin said disk and the par- .titions carriedthere y.

3. A rotary machine comprising a rotor formed with a plurality ofradially-directed cylinders fitted With pistons, a pin secured to thestator with its axis parallel to that of the rotor at a distancetherefrom equal to half the stroke of the pistons, a strap embracingsaid pin, rods connecting said strap to all but one of said pistons by apin-connection, the rod of the latter being formed integrally With thestrap, an inclosing stator which provides an annular space around saidrotor, a assage leading to said annular space an one leading therefromthe ports of which are situated approximately at the extremities of adiameter of the stator which contains the center of the orbit of thepistons, partitions situated approximately diametrally opposite eachother and carried by a disk and means for angularly displacing said diskand the partitions carried thereby.

4. A power-transmitter of variable speedratio, comprising a combinationof a rotary pump and a rotary motor in Which the pump and also the motorcomprise a rotor formed With a plurality of radially-directed cylindersfitted With pistons, means for connecting said pistons to the statorsuch that they pursue an orbital path eccentric to the axis of therotor, an inclosing stator which provides an annular space around saidrotor, a passage leading to said annular space and one leading therefromthe ports of which are situated approximately -at the extremities of adiameter of the stator which contains the center of the orbit of thepistons, partitions situated approximately diametrally opposite eachother and carried by a disk and in one element of the pump-motorvcombination means for angularly displacing said disk and the partitionscarried thereby.

5. A power-transmitter of variable speedratio, comprising a combinationof a rotary pump and a rotary motor in which the pump and also the motorcomprise a rotor formed with a plurality of radially-directed cylinderstted With pistons, a pin secured to the stator with its axis parallel tothat of the rotor at a distance therefrom equal to half the stroke ofthe pistons, said pin of pump being formed integrally with said pin ofmotor, a strap embracing said pin, rods connecting said strap to all butone of said pistons by a pin connection the rod of the latter beingformed integrally with the strap, an inclosing stator which provides anannular space around said rotor, a passage leading to said annular spaceand one leading therefrom the ports of Which are situated approximatelyat the extremities of a diameter of the stator which contains the Intestimony whereof I have signed my center of the orbit of the pistons,partitions name to this specification in the presence of situatedapproximately 'diametrally oppotWo subscribing Witnesses.

site each other and carried by a disk and in LEWIS ERNEST HOPKINS. oneelement of the pump-motor combina- Witnessesz tion means 'for angularlydisplacing said A. W. FINNooK,

disk and the partitions carried thereby. ALBERT' S. PHILLIPS.

